Naomi Watts reveals Princess Di makeover

Naomi Watts is diving head first into her role as Princess Diana. Photo / AP

The first pictures of Naomi Watts as Princess Diana have emerged online.

The British-born actress, 43, has been cast as the late royal in director Oliver Hirschbiegel's upcoming drama Caught In Flight, which will focus on the last two years of the beloved Princess's life.

The film - which was previously rumoured to featureThe Help star Jessica Chastain in the lead role - is believed to explore Diana's relationship with heart surgeon Hasnat Khan, as well as Dodi Fayed, and will include her death, aged 36, in a car crash in a Paris tunnel in 1997.

Oscar-nominated Watts, whose screen credits include movies such as Mulholland Drive, King Kong and J Edgar, said of her casting earlier this year: "It is such an honour to be able to play this iconic role - Princess Diana was loved across the world and I look forward to rising to the challenge of playing her on screen."

The actress also told the Press Association: "She is a part of our history, an incredible woman and fascinating but (suffered) a tragic ending. The filmmakers came to me and it's a good script and it's very scary and I kind of wanted to say no but I couldn't.

"I saw the wedding (Diana's 1981 wedding to Charles, Prince of Wales) and everything and she is a very inspiring woman and it's kind of impressive how she sort of changed the whole gearing of the tradition of the royal family and opened it up and brought warmth to it."

Hirschbiegel added: "I am delighted to have such a truly exceptional actress who embodies the warmth, humanity and empathy of such a global icon as Princess Diana."

Khan will be played by Lost actor Naveen Andrews, who recently praised Watts as perfectly cast for the role.

"I don't think anyone else could have done it - there's no one else," Andrews said.

He added: "Whenever you work, usually if something has a chance or the potential to be good it usually starts with a good script and I'm very happy with the script and Naomi is doing it and she's wonderful ... I'm very much looking forward to shooting."

On Tuesday, Watts was snapped stepping out on the set of the movie in London, wearing replicas of outfits worn by the Princess, and sporting Diana's trademark mid-90s haircut.

Watts donned a black blazer, pencil skirt and heels while filming one scene.

She was later spotted in an evening dress and with immaculately coiffed short blonde hair, while filming a scene outside the Royal Opera House.